Formation tester



J. T. woon; JR., x-:TAL

May 15, 1945.

FORMATION TESTER Filed May 27, 1941 V,JAMES T. wooo JR.

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Patented May l5, 1945 FORMATION TESTER James T. Wood, Jr., San Marino, and Eugene L. Davis, Long Beach; Calif., assignors, by mesne'l assignments, to The Texas Company, New York, N. Y., a corporation of Delaware Application May 27, 1941, serial No. 395,342

3 Claims.

This invention relates to an apparatus for testing sub-surface formations, and more particularly to an apparatus by means of which a sample of a fluid may be taken from a formation travformations to be tested are encountered andto provide surface casing sufficiently large that the hole may be reamed out at least three inches larger than the small hole so as to provide a shoulder on which a packer may be seated incase any sands worth testing are encountered. It is also fairly common lto drill a reasonably large hole and then, when a producing formation is encountered or expected, to reduce the diameter of the hole and to drill ahead until there is a sulciently good showing to justify a test. In either case, a large hole must be drilledand in some cases either two strings of drill pipe are necessary or a string o-f mixed sizes is used. Both of these methods are objectionable from an operating standpoint since the cost of a hole obviously increases rapidly in proportion to the hole diameter. l

Up to the present time no satisfactory method of testing formations has been devised whereby dependable tests can be made in a holeof uniform size since it is impractical to form an adequate seal between the drill pipe and the wall of the hole by the known types of -wall packers. This is particularly true in deep wells where the weight of the superimposed drilling mud uid is greater than can be packed olf tightly without some sort of shoulder on which a packer may rest so as to carry the Weight of this column of fluid.

In accordance with the present invention, an apparatus has been devised for testing -formations at the bottom of deep, small diameter, drill holes without the necessity of reaming the hole all the Way in order to provide clearance for running a packer and then making a shoulder near the bottom of the hole on which to seat the packer. Other types of well fluid testers which attempt to form a fluid seal against thewall of the drill hole Without a shoulder are generally ,unsuccessful in deep wells.

In carrying out the invention a hole of relatively small diameter is drilled suflciently deep to penetrate the formation to be tested, after which a small section of the hole is enlarged as by under-reaming so as to form a shoulder above the vformation to be tested. A string of drill pipe or tubing is then runinto the hole, the lower end of this string supporting a pipe member or section containing perforations through which the fluid from the formation may pass. Above the perforated pipe section is a packing device which, when collapsed, will be suiflciently small iii-diameter toA pass downwardly through the small hole into the under-reamed poition. The packing device is provided with a tapered mandrel adapted to be lowered and actuated to expand the packer when the packer is opposite the lower shoulder of the under-reamed section, and the weight of the mud uid in the hole above the packer will then be carried on the shoulder. A valve in the packing device is then opened allowing the fluid from the formations *below the packer to pass upwardly into the drill pipestring, after which the valve is again closed, trapping the fluid within the pipe. yThe packer is then collapsed and the entire pipe string, including the packing device, is removed from the hole.

For aA better understanding of the invention, reference may be had to the accompanying drawing in which Fig. 1 is 'a vertical longitudinal section through an apparatus embodying the invention Flgf2 is a vertical longitudinal section showing the apparatus in a hole with the packer expanded and the valve open to allow fluid to enter the string of drill pipe, and

Fig. 3 is a cross-section taken on the line 3 3' ofFig.1. f'

Referring to the drawing, a string of drill pipe I0 is provided at its lower end with a perforated pipe section or strainer I2 closed at the bottom by means of the plate I4 adapted to rest `on the u bottom of a drill hole IB. Above the strainer I2 is another pipe section I8 upon which is threaded a ring 20, the ring and the pipe section I8 being formed with a groove 22 adapted to hold'the lower end of a exible packing element 24. which surrounds the pipe I8; Above the packer 24 and vertically slidable on the pipe I8 is a mandrel 26,

the lower portion of which is tapered to flt a similarly tapered upper portion ofthe packer 24. The'mandrel 26 is provided along its in'terna1 surface with a vertical groove 28 having'an L-shaped portion 3II. A lug. 32 is provided on the outer surface of the pipe I8 and is adapted to flt'wlthln the groove 28 so that there can bea slight angular movementbetween the mandrel 26 and the pipe I8, as well as a vertical movement determined by the length of the vertical portion of the groove 28. Suitable packing 34 is provided betweenthe 2, mandrel 26 and the pipe I8. The upper end of the mandrel 26 is screw threadedly connected to a sub 36 to the upper end of which is connected a second sub 38, the top of sub 38 being screw threadedly connected to the lower end of the drill pipel I0.

The upper end of the pipe section I8 is provided with a downwardly opening .disc valve 40 cooperating with a seat in an inwardly projecting flange. or shoulder 4l at the upper end of the pipe i8, the valve 40 being normally held in its upper or closed position by a compression .spring 42 abutting against the shoulder 4I and `a vertically slidable spider 44 attached to the valve by means of a stem 36. Mounted in the joint between the upper end of the mandrel 26 and the sub 36, and extending downwardly within the mandrel, is a spring 48 for a purpose to be described. Mounted within the joint between the two subs 36 and 38 is a bridge or spider-shaped member 50, also shown in Fig. 3, and at the joint between sub 38 and drill pipe I is mounted a frangible disc 52.

The device which has 'been described is adapted to be lowered into a drill hole I6 of a relatively small diameter such as is often used for exploring and testing purposes. A section 56 of the hole is enlarged as by under-reaming so that a shoulder 58 will be `formed between the bottom of the enlarged section and the lower portion of the hole I6. The under-reamed, portion 56 of the hole is formed so that there will be a predetermined distance between shoulder 58 and the bottom of the hole. It is understood that the bottom portion of the hole IB below the shoulder 58 has been drilled into a formation 60, the fluid content of which it is desired to analyze,

In operation, the device made up, as shown in Fig. 1, is lowered into the hole i6 until the -plate I4 reaches the Ibottom of the hole. 'I'he packer 24 will then be opposite the shoulder I58. When in this position, the drill pipe string carrying the mandrel 26 is lowered slightly until the lug 32 is in the horizontal portion of the slot 28 whereupon the pipe string is partially rotatedand again lowered, the lug 32 cooperating with the longer, vertical portion of the slot 28. The tapered portion of the mandrel 26 will expand the flexible packing element 24 against the shoulder 58 thus forming a fluid tight seal. Lowering the mandrel 26 also lforces the spring 48 to abut against the spider 44l thus compressing the spring 42 and opening the valve 48, permitting fluid from the formation to pass upwardly through the strainer l2 and into the upper portion of the mandrel 26 above the valve 40. A small bar 62, usually termed a go devil, is then dropped through the pipe string, the bar breaking the frangible disc 52 and stopping upon the spider member or bridge 50. This permits the fluid from the formation to pass on upwardly into the drill pipe I0. At the conclusion of the test the drill pipe l0 and mandrel 26 are raised permitting the spring 42 to close the valve 40 to trap the formation fluid and the drill pipe is then partially rotated to reseat the lug 32 in the L-shaped portion 38 of the slot 38 thereby locking the pipe I8 to the drill string l0. The packer 24 will then assume its original position, as shown in Fig. 1, and the drill pipe string and the packing device, as shown in Fig. 1, are withdrawn from the hole after which the fluid trapped above the valve 40 is removed n from the pipe for testing purposes.

Obviously, many modifications and variations of the invention as hereinbefore set forth may be made without departing from the spirit .and

scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

l. A device for sampling fluid from a formation traversed by a small drill hole containing an enlarged portion near the bottom thereof, which comprises a string of drill pipe, a pipe section having a strainer at its lower end and said section being disposed below said drill pipe, a flex ible packing element secured to said pipe section above said strainer, means for expanding said packing element to set it on the shoulder between the .bottom of said enlarged hole portion and the lower portion of said hole, said expanding means comprising a mandrel suspended vfrom the bottom of said drill pipe and having telescoping engagement with a portion of said pipe section, said mandrel and said flexible packing element having tapered portions so that movement of the tapered portion of the mandrel into the packing element causes expansion of said packing element, a valve normally closed in said pipe section above said strainer, an abutment attached to said expanding means and adapted to engage and open said valve when the packing element is being set, and resilient means for closing said valve when the packing element is released.

2. A device for sampling iluid from a formation traversed by a small drill hole containing an enlarged portion near the bottom thereof, which comprises a string of drill pipe, a pipe section disposed below the lower end of said drill pipe, a strainer attached to the lower end of said pipe section, a packing element secured to said-pipe section above said strainer, means for setting said packing element on the shoulder between the bottom of' said enlarged hole portion and the lower portion of said hole, said expanding means comprising a mandrel suspended from the bottom of said drill pipe and having telescoping engagement with a portion of said pipe section, said mandrel and said flexible packing element having respective inwardly and outwardly tapered portions so that movement of the tapered pory tion of the mandrel into the packing element causes ylexpansion of said packing element, a frangible member normally closing the lower end of said pipe string, means for breaking said frangible member to permit well fluid to pass through said strainer and upwardly in said pipe string, valve means in said pipe section below said frangible member, an abutment attached to said packer setting means and adapted to engage and open saidvalve means on downward movement of said mandrel, and resilient means for closing said valve means on upward movement of the mandrel.

3, A device for sampling fluid from a formation traversed by a small drill hole containing an enlarged portion near the bottom thereof, which comprises a string of drill'pipe, a strainer pipe section :below said drill pipe, a flexible packing element secured to said pipe section aboveY said strainer, means for setting said packing element fon the shoulder between the bottom of said enlarged hole portion and the lower portion of said ment being such that on a predetermined lowering movement of said drill pipe string said mandrel will expand said packing element into engagement with said shoulder, a -frangible memlber closing the interior of said pipe string, means mi@ @mangime memex inermi?,

@um to ms@ 1w..- sd simmer and up www im :m pipe swing, said bre means amprisimg a bar adapted to he dropped, through @me pipe fw stmk@ and break smd member, @iw means m said plm gestion below fr im@ member, xesiln. means m5,', hed to and @Siusi Said valve to JS T. WOOD, JRn A EUGENE L. DA. 

